Hyperbaric oxygen was safe and effective for treating patients with COVID-19 and severe hypoxemia, according to a prospective, multicentre study from Argentina recently published in the Emergency Medicine Journal.¹

Forty patients, mean age 55.2 years, with Covid-19 and severe hypoxia with SpO2 ≤90% even with oxygen supplementation, were selected for this open-label, randomized controlled trial conducted from July to November 2020. All patients were given the standard treatment for Covid-19, while one group of 20 patients also received hyperbaric oxygen in 6.2 sessions (average) - one per day -  of 90 minutes at 1.45 atmosphere absolute (ATA) for seven days. The outcomes of the study were time to normalize oxygen requirement to SpO2 ≥93%, need for mechanical respiratory assistance, development of acute respiratory distress syndrome (ARDS) and mortality within 30 days.

The most common symptoms at the time of randomization were dyspnea, fever and odynophagia. The overall baseline mean SpO2 was 85.1% (86.5% in the hyperbaric oxygen treatment group and 84.1% in the control group).

Hypoxemia was corrected (SpO2 ≥93%) within 3 days in the hyperbaric oxygen group as against 9 days in the standard treatment only group. Compared with the control group, the likelihood of improvement of hypoxia was higher in the patients treated with hyperbaric oxygen with odds ratio (OR) of 23.2 at day 3 and 28.5 at day 5. In these patients, SpO2 showed an immediate and successive daily improvement at a higher slope. No significant effect of hyperbaric oxygen treatment was seen on ARDS, mechanical ventilation or mortality within 30 days, which could be a limitation of this study attributed to the smaller study population and “selection of possibly a less critical cohort of patient”.2

Severity of hypoxia, as is now well-established, is an important predictor of mortality in patients with Covid-19. Timely correction of hypoxia therefore is an important treatment goal to improve patient outcomes. This study illustrates the adjuvant role of hyperbaric oxygen in the treatment of hospitalized Covid-19 patients with severe hypoxemia. “HBO has a direct effect on oxygen absorption and its delivery to the body’s tissues, and therefore increases oxygen saturations”.²

Correction of hypoxia was faster in the treatment group vis-à-vis control group as demonstrated in this study. No significant adverse effects of the treatment were observed. The study was stopped early at interim analysis because of the observed clinical benefits for superiority and safety. The treatment pressure of 1.4 ATA employed in this study is the minimum therapeutic level for clinical hyperbaric oxygen use. It is safer to use hyperbaric oxygen at lower to medium pressure (below 2 ATA) than at higher pressures.

This study suggests that even a few sessions of hyperbaric oxygen treatment, using portable hyperbaric chambers could be of help to patients in the Emergency department before they are shifted to ICUs.

Reference

1. Cannellotto M, et al. Hyperbaric oxygen as an adjuvant treatment for patients with COVID-19 severe hypoxaemia: a randomised controlled trial. Emerg Med J. 2021 Dec 14;emermed-2021-211253. doi: 10.1136/emermed-2021-211253.
2. Kirby J, et al. Hyperbaric oxygen therapy for patients with COVID-19. Emerg Med J. 2021 Dec 14;emermed-2021-212015. doi: 10.1136/emermed-2021-212015.